How do cows keep producing milk?
After the cow has her first calf her mammary system contains aveoli cells that begin to produce milk which is stimulated by the prolactin hormone. The cow does not need to become pregnant again to continue milking and actually if the cow does become prengant the amount of milk produced will decrease as part of the feed intake is diverted to the growing fetus. If the cow does not become pregnant again she will continue milking until her genetic ability and quality of feed intake diminishes. We have had cows milk for 2 to 3 years following the birth of their calf without being pregnant.
